A 15-year study has found that infants fed formula made from cow’s milk do not have an increased risk of developing type 1 diabetes.

The rate of diagnosed cases of type 1 and type 2 diabetes has been on the rise in the US, with an estimated 29.1m people under the age of 20 living with diagnosed diabetes, according to a 2017 report by the New England Journal of Medicine.

While obesity has been strongly linked to the development of type 2 diabetes, the cause of type 1 disease remains largely unknown. Past studies have indicated early exposure to complex foreign proteins, such as cow’s milk proteins, increases the risk of type 1 diabetes for individuals with a genetic predisposed risk to type 1 diabetes.

The recently-published international TRIGR Study followed 2,159 infants from 15 countries, each with a family member affected by type 1 diabetes or with a genetic risk for type 1 diabetes, to determine whether delaying exposure to complex foreign proteins decreases the risk of diabetes.

After breastfeeding for at least two months, half of the infants were given the study formula containing regular cow’s milk proteins, while the other half received “extensively hydrolyzed casein”​ formula with cow’s milk proteins split into small peptides, according to the study

Both groups avoided cow’s milk proteins from all other food sources. The trial lasted until the youngest subject turned 10-years-old.

The results show that in this large international randomized trial, weaning to an extensively hydrolyzed casein formula during infancy did not result in a reduction in the incidence of type 1 diabetes compared to regular intact cow's-milk-based formula after about 11.5 years of follow up.

The study’s researchers added that there is no evidence to revise the current dietary recommendations for infants at high risk for type 1 diabetes.

"After more than 15 years of effort, this study puts to rest the controversy regarding the potential role of cow's milk formula in the development of type 1 diabetes,"​ said Dr Dorothy Becker, the study's chief US collaborator, at Children's Hospital of Pittsburgh, in a statement.

"This once more shows us that there is no easy way to prevent type 1 diabetes."​